Handheld electronic device and associated method enabling text input in a language employing non-roman characters

ABSTRACT

A handheld device includes a plurality of input members, a first set of which each have a Roman character assigned thereto, a least some of which have a first non-Roman, second non-Roman character, and third non-Roman characters assigned thereto. The device is switchable between first and second modes. In the first mode, each Roman character may be input in response to actuation of the input member to which it is assigned, and in the second mode, each first non-Roman character may be input in response to a first type of actuation of the input member to which it is assigned, each second non-Roman character may input in response to a second type of actuation of the input member to which it is assigned, and each third non-Roman character may be input in response to a third type of actuation of the input member to which it is assigned.

CROSS-REFERENCED TO RELATED APPLICATION

The present application claims the benefit of U.S. Provisional PatentApplication Ser. No. 61/051,831, entitled “HANDHELD ELECTRONIC DEVICEAND ASSOCIATED METHOD ENABLING TEXT INPUT IN A LANGUAGE EMPLOYINGNON-ROMAN CHARACTERS” filed May 9, 2008, the disclosure of which isincorporated herein by reference.

BACKGROUND

1. Field

The disclosed and claimed concept relates generally to handheldelectronic devices and, more particularly, to a handheld electronicdevice and method that enable the input of text in a language, such asthe Thai language, that employs characters other than Roman characters.

2. Background Information

Numerous types of handheld electronic devices are known. Examples ofsuch handheld electronic devices include, for instance, personal dataassistants (PDAs), handheld computers, two-way pagers, cellulartelephones, and the like. Many handheld electronic devices also featurewireless communication capability, although many such handheldelectronic devices are stand-alone devices that are functional withoutcommunication with other devices.

Such handheld devices are often used by people that speak multiplelanguages. Many languages, including the English language, use Romancharacters (sometimes also referred to as Latin characters), and thuswhen a user wishes to input text into a handheld electronic device insuch a language, a keyboard including Roman characters, such as astandard QWERTY keyboard, provided as part of the device may be used.However, some languages employ, either partially or entirely, a set ofnon-Roman characters. One such language is the Thai language. Inparticular, the Thai alphabet employs 71 non-Roman characters includingconsonants, vowels, tones and diacritics. It would be desirable for akeyboard on a handheld electronic device to provide the ability to entertext using these 71 characters. However, a typical QWERTY keyboardemployed on a handheld electronic device has 28 character keyscorresponding to the Roman characters. Therefore, a regular QWERTYkeyboard cannot accommodate all 71 characters used in Thai script. Itthus would be desirable to provide an improved method and handheldelectronic device that facilitate the input of text in a language, suchas the Thai language, that employs characters other than Romancharacters.

BRIEF DESCRIPTION OF THE DRAWINGS

A full understanding of the disclosed and claimed concept can be gainedfrom the following Description when read in conjunction with theaccompanying drawings in which:

FIG. 1 is a schematic representation of an improved handheld electronicdevice according to an embodiment of the disclosed and claimed concept;

FIG. 2 is a schematic representation of an embodiment of a keyboardforming a part of the exemplary handheld electronic device shown in FIG.1;

FIG. 3 is a schematic representation of a symbol screen of the exemplaryhandheld electronic device shown in FIG. 1;

FIGS. 4A, 4B, 4C are flowcharts illustrating various aspects of a methodfor facilitating the entry of text having non-Roman characters using theexemplary handheld electronic device shown in FIG. 1 according to anembodiment of the disclosed and claimed concept;

FIGS. 5-15 illustrate an example input sequence performed on theexemplary handheld electronic device shown in FIG. 1; and

FIG. 16 is a schematic representation of an alternate embodiment of akeyboard forming a part of the exemplary handheld electronic deviceshown in FIG. 1.

Similar numerals refer to similar parts throughout the specification.

DESCRIPTION

An improved handheld electronic device 4 is depicted schematically inFIG. 1. The exemplary handheld electronic device 4 includes a housing(not shown), an input apparatus 8, an output apparatus 12, and aprocessor apparatus 16. The input apparatus 8 is structured to provideinput to the processor apparatus 16, and the output apparatus 12 isstructured to receive output signals from the processor apparatus 16.The output apparatus 12 comprises a display, such as an LCD or atouchscreen, that is structured to provide visual output, although otheroutput devices such as speakers, LEDs, tactile output devices, and soforth can be additionally or alternatively used.

As can be seen in FIG. 1, the processor apparatus 16 comprises aprocessor 36 and a memory 40. The processor 36 may be, for instance andwithout limitation, a microprocessor (μP) that is responsive to inputsfrom the input apparatus 8 and that provides output signals to theoutput apparatus 12. The processor 36 interfaces with the memory 40.

The memory 40 can be said to constitute a machine-readable medium andcan be any one or more of a variety of types of internal and/or externalstorage media such as, without limitation, RAM, ROM, EPROM(s),EEPROM(s), FLASH, and the like that provide a storage register for datastorage such as in the fashion of an internal storage area of acomputer, and can be volatile memory or nonvolatile memory. The memory40 has stored therein a number of routines 44 which are executable onthe processor 36. As employed herein, the expression “a number of” andvariations thereof shall refer broadly to any non-zero quantity,including a quantity of one. The routines 44 can be in any of a varietyof forms such as, without limitation, software, firmware, and the like.As will be explained in greater detail below, the routines 44 includeone or more routines that implement a method of facilitating the inputof text into the handheld electronic device 4 in a language, such as theThai language, that employs characters other than Roman characters, aswell as other routines. It is noted that the Thai language is used as anexemplary language herein, and it is further understood that otherlanguages that employ characters other than Roman characters, such as,without limitation, Chinese, Japanese and Korean, for example, couldsimilarly be input on the handheld electronic device 4 using the methoddescribed herein without departing from the present concept. That is,the handheld electronic device 4 is described herein in an exemplaryfashion as being configured for the inputting of Thai script, and it isunderstood that in other embodiments the handheld electronic devicecould be configured to input, for instance, Chinese, Japanese or Koreantext or text in another language employing non-Roman characters withoutdeparting from the present concept.

The input apparatus 8 is shown schematically in FIG. 2 and includes akeyboard 24 and a multiple-axis input device which, in the exemplaryembodiment depicted herein, is a track ball 32 that will be described ingreater detail below. The keyboard 24 comprises a plurality of keys 28arranged in the exemplary form of a QWERTY keyboard, meaning that atleast some of the keys 28 each have a plurality of linguistic elementsassigned thereto, with at least some of the linguistic elements beingRoman characters arranged generally in a QWERTY configuration and someof the linguistic elements being Thai characters. In particular, as seenin FIG. 2, each key 28 having a Roman character thereon also has up tothree Thai characters also provided thereon. Up to two characters may beprovided below the Roman character on the key 28, and one Thai charactermay be provided adjacent to the Roman character on the key 28. The keys28 or the track ball 32 serve as input members that are actuatable toprovide input to the processor apparatus 16. The particular operation ofthe keyboard 24 to facilitate the input of text in the Thai languageaccording to the disclosed and claimed concept is described in greaterdetail below. The keyboard 24 and the track ball 32 are advantageouslydisposed adjacent one another on a front face of the housing of thehandheld electronic device 4. This enables a user to operate the trackball 32 substantially without moving the user's hands away from thekeyboard 24 during a text entry operation or other operation.

One of the keys 28 is an <ESCAPE> key 31 which, when actuated, providesto the processor apparatus 16 an input that undoes the action whichresulted from the immediately preceding input and/or moves the user to alogically higher position within a logical menu tree managed by agraphical user interface (GUI) routine 44. The <ESCAPE> key 31 isadvantageously disposed adjacent the track ball 32 thereby enabling, forexample, an unintended or incorrect input from the track ball 32 to bequickly undone, i.e., reversed, by an actuation of the adjacent <ESCAPE>key 31. Another of the keys 28 is a <MENU> key 33 which, when actuated,provides to the processor apparatus 16 an input that causes the GUI 44to generate and output on the output apparatus 12 a menu for selectingoperations and operational modes of the handheld electronic device 4.

While in the depicted exemplary embodiment the multiple-axis inputdevice is the track ball 32, it is noted that multiple-axis inputdevices other than the track ball 32 can be employed without departingfrom the present concept. For instance, other appropriate multiple-axisinput devices could include mechanical devices such as joysticks and thelike and/or non-mechanical devices such as touch pads, track pads andthe like and/or other devices which detect motion or input in otherfashions, such as through the use of optical sensors or piezoelectriccrystals. Likewise, in other exemplary embodiments, the keyboard 24 canbe a virtual keyboard on the output apparatus 12.

The track ball 32 is freely rotatable in all directions with respect tothe housing of the handheld electronic device 4. A rotation of the trackball 32 a predetermined rotational distance with respect to the housingprovides an input to the processor apparatus 16, and such inputs can beemployed by the routines 44, for example, as navigational inputs,scrolling inputs, selection inputs, and other inputs. The track ball 32additionally is translatable toward the housing to provide additionalinputs. The track ball 32 could be translated in such a fashion by, forexample, a user applying an actuating force to the track ball 32 bypressing on the track ball 32. The inputs that are provided to theprocessor apparatus 16 as a result of a translation of the track ball 32in the indicated fashion can be employed by the routines 44, forexample, as selection inputs, delimiter inputs, or other inputs.

In accordance with the disclosed and claimed concept, the handheldelectronic device 4 through cooperation between the routines 44 and thekeyboard 24 advantageously enables text input in the Thai language usingthe Thai characters provided on the keys 28. In particular, in theexemplary embodiment, the handheld electronic device 4 may be toggledbetween a Roman character input mode, in which the Roman charactersprovided on the keys 28 may be selectively input through actuation ofthe keys in a conventional manner, and a Thai character input mode, inwhich the Thai characters provided on the keys 28 may be selectivelyinput through actuation of the keys 28 in the manner described herein.Such toggling may be achieved by, for example, making an appropriateselection from a menu accessed through actuation of the menu key 33.

In the exemplary embodiment, when the handheld electronic device 4 is inthe Thai character input mode, one or more Thai characters providedbelow the Roman character on each key 28 may be selected and input usinga multi-tap scheme. Specifically, the first (left-most) Thai characterprovided below the Roman character on each key 28 may be selected andinput by pressing the corresponding key 28 once, and the second(right-most) Thai character provided below the Roman character on eachkey 28 may be selected and input by pressing the corresponding key 28twice within a predetermined time frame. Preferably, when thecorresponding key 28 is pressed once, the first Thai character providedbelow the Roman character on the key 28 will be entered and displayed,and will be highlighted or underlined until the predetermined time frameelapses or until a different key 28 is pressed to indicate thepossibility that the key 28 could be pressed again to get the secondThai character provided below the Roman character on the key 28. If thesame key 28 is pressed twice with more than the predetermined time frameelapsing between each press, the first Thai character provided below theRoman character on the key 28 will input twice. The Thai character, ifany, provided adjacent to the Roman character on each key 28 is providedon the SHIFT layer of the keyboard 24 and may be selected and input bypressing one of the <SHIFT> keys 35 and then pressing the key 28 havingthe desired Thai character.

FIGS. 4A and 4B are flowcharts illustrating the method of entering Thaicharacters in the exemplary embodiment described above. Beginning atstep 50, a determination is made as to whether the processor 36 hasreceived an input indicating a switch to the Thai character input mode.If the answer is no, then the method returns to step 50. If, however,the answer is yes, then, at step 52, a determination is made as towhether an actuation of a key 28 has been detected. If the answer is no,then, at step 54, a determination is made as to whether the processor 36has received an input indicating a switch to the Roman character inputmode. If the answer is yes, then method ends. If the answer is no, thenthe method returns to step 52.

If the answer at step 52 is yes, meaning that an actuation of a key 28has been detected, then, at step 56, a determination is made as towhether the processor 36 is currently in a shift mode. If the answer isyes, then, at step 58, the Thai character on the shift layer of theactuated key 28 is input and displayed on the output apparatus 12. Then,at step 60, a determination is made as to whether the processor 36 hasreceived an input indicating a switch to the Roman character input mode.If the answer is yes, then the method ends. If, however, the answer isno, then the method returns to step 52.

If the answer at step 56 is no, meaning that the processor 36 is notcurrently in the shift mode, then at step 62, the first Thai characterbelow the Roman character of the actuated key 28 is input into theprocessor 36 and displayed and highlighted on the output apparatus 12.The method then proceeds to FIG. 4B.

Referring to FIG. 4B, at step 64, a timer having a duration equal to thepre-determined timeframe for multi-tap entry described above is started.Next, at step 66, a determination is made as to whether the processor 36has detected the actuation of one of the keys 28. If the answer is no,then, at step 68, a determination is made as to whether the timer haselapsed. If the answer is no, then the method returns to step 66. If theanswer is yes, then, at step 70, the highlighting applied in step 62 isremoved and the method returns to step 52 of FIG. 4A. If the answer atstep 66 is yes, meaning that a key 28 has been actuated, then, at step72, a determination is made as to whether it is the same key that wasactuated in step 52. If the answer is no, then the method returns tostep 56 in FIG. 4A. If the answer, however, at step 72 is yes, meaningthat the same key 28 has been actuated, then, at step 74, the first Thaicharacter currently displayed on the output apparatus 12 is replacedwith the second Thai character below the Roman character on the key 28that has been actuated (for the second time). Then, the method returnsto step 52 of FIG. 4A.

In the exemplary embodiment, seldom used Thai characters are provided ona symbol screen 37 shown in FIG. 3 that may be accessed and displayed onthe output apparatus 12 by pressing the <SYMBOL> key 37 of the keyboard24. A desired Thai character may then be selected and input by pressingthe key 28 shown to correspond to the desired Thai character on thesymbol screen 37.

Moreover, Thai script is written left to right and consists of threelevels, meaning that the individual characters may be positioned in oneof three locations (levels): a base level, an above level (above thebase level), and a below level (below the base level). The base level iswhere consonants, leading and following vowels, special characters andnon-Thai characters are positioned. The above level is where abovevowels, tones and above diactrics are positioned. The below level iswhere below vowels and below diactrics are positioned. In addition, theThai language includes certain rules that prohibit certain charactercombinations, such as certain character appearing in sequence. Forexample, two “sara i” characters are not permitted to appearsequentially. In addition, “sara e” (

), representing a leading vowel, cannot be followed by “sara a” (

), representing a following vowel, without at least a consonant betweenthem. Certain following vowels may follow other following vowels, suchas “sara o” (

). The Thai language also includes certain rules that prohibit word fromstarting with certain vowels. Those vowels include the “maiyamok”character, the “sara am” character, the “sara a” character, the “sara u”character, the “mai han-akat” character, the “sara ue” character, the“sara uu” character, the “sara ii” character, the “mai tho” character,the “mai ek” character, the “mai tri” character, the “sara aa”character, the “mai chattawa” character, the “sara i” character, the“sara uee” character, the “phintu” character, and the “thanthakhat”character. Other prohibitions are also possible either within the Thailanguage if applicable, or another language employing non-Romancharacters, as appropriate. Thus, according to an aspect of thedisclosed and claimed concept, the routines 44 that implement the methoddescribed herein prevent the user of the handheld electronic device 4from entering illegal/non-permitted character sequences, and in certaincircumstances will automatically input another character on the pressedkey 28 that includes the non-permitted character in the place of thenon-permitted character. In effect, by doing so, the routines in certainsituations temporarily “convert” a multi-tap key into a single characterkey. It is noted that the foregoing input entry method routines 44 arenot limited to Thai script, and can also be adapted for other languagesto prevent the user from inputting a non-permissible sequence ofcharacters.

FIG. 4C is a flowchart illustrating the method just described. Themethod begins at step 76, wherein the processor 36 receives an inputrequesting the entry of a Thai character (this may be any of the keyactuations described in connection with FIGS. 4A and 4B). Then, at step78, the processor 36 determines the immediately preceding Thai characterthat was input and displayed. It should be noted that in step 78, in thecase of a new word, the processor 36 will determine that there is noimmediately preceding character (instead, the immediately precedinginput will have been a space). Thus, the immediatly preceding characterin the method of FIG. 4C may be “none.” At step 80, a determination ismade as to whether the proposed sequence is permissible based upon theapplicable language rules as described above. If the answer is yes,then, at step 82, the requested Thai character is input and displayed onthe output apparatus 12. If the answer at step 80 is no, then, at step84, the processor 36 prevents the input and display of the requestedThai character. Then, at step 86, according to one particular embodimentof the disclosed and claimed concept, the processor 36 will then inputand display on the output apparatus 12 another (different) Thaicharacter provided on the key that includes the requested Thaicharacter. An example of this type of automatic substitution is shown inconnection with FIGS. 5 through 15. Step 86 may, alternatively, beomitted, in which case the processor 36 would simply prevent the inputand display of the requested Thai character. In this embodiment, amessage may be displayed to the user on the output apparatus 12indicating that the proposed sequence is not permissible and instructingthe user to make another character selection.

FIGS. 5-15 illustrate an example input sequence wherein the user types agreeting in Thai script by pressing certain of the keys 28 when thehandheld electronic device 4 is in the Thai character input mode.Specifically, FIGS. 5-15 show a screen 40 displayed on the outputapparatus 12 having a text portion 42 resulting from the pressing of anumber of the keys 28 when the handheld electronic device 4 is in theThai character input mode.

Referring to FIG. 5, the user in this example has initially pressed the<J> key 28 once and then pressed the <K> key 28 once. This results inthe entry of the “so suea” character followed by the “wo waen”character, which are displayed in the text portion 42 as seen in FIG. 5.In addition, the predetermined time frame for multi-tap input describedabove has passed, and thus the “wo waen” character is not highlightedand the cursor 44 is positioned adjacent thereto. Next, referring toFIG. 6, the <T> key 28 is pressed once, which results in the entry ofthe “mai han-akat” character. The “mai han-akat” character is an abovevowel, and thus, as seen in FIG. 6, it is positioned in the above levelabove the previous character (the “wo waen” character). In addition, inthe case of FIG. 6, the predetermined time frame for multi-tap inputdescribed above has not yet passed, and thus the “wo waen” and “maihan-akat” characters are highlighted in the text portion 42, indicatingthat multi-tap entry is still available (to get the “sara ue” characterwhich is the second Thai character appearing below the “T” on the <T>key 28). If the predetermined time frame for multi-tap input elapseswithout further input form the user or if the user presses the <SPACE>key 39, the “mai han-akat” character will be confirmed in the textportion 42 as shown in FIG. 7 and the cursor 44 will appear adjacentthereto.

Next, referring to FIGS. 8 and 9, the user presses the <J> key 28 onceand then the <S> key 28 once, which results in the entry of the “sosuea” character followed by the “ko kai” character in the text portion42 shown in FIG. 8. The user then, before the predetermined time framefor multi-tap input has elapsed, again presses the <S> key 28, whichresults in the “ko kai” character being replaced by the “do dek”character in the text portion 42 as shown in FIG. 9. The user thenpresses the <Y> key once, which results in the entry of the “sara 1”character in the text portion 42 as shown in FIG. 10. The user thenwaits for the predetermined time frame for multi-tap input to elapse,which results in the text portion 42 shown in FIG. 11 (the cursor 44 ispositioned adjacent to the last Thai character). The user then pressesthe <Y> key again with a single press. However, in Thai script, twosequential “sara i” characters are not permitted. As discussed elsewhereherein, the routines 44, according to an aspect of the disclosed andclaimed concept, are programmed with the sequential character rules ofThai script. As a result, the routines 44 automatically cause the othercharacter provided below the “Y” on the <Y> key 28, which is the “dodek” character, to be entered in the text portion 42 as shown in FIG. 12instead of the “sara i” character. Finally, the user presses the <U> key28 once followed by the <T> key 28 once followed by the <P> key 28 once,which results in the entry of the “ro ruea”, “mai han-akat” and “bobaimai” characters, respectively, into the text portion 42 as shown inFIGS. 13-15 (each those characters is the first multi-tap choice ontheir respective keys 28).

FIG. 16 is a schematic representation of alternate embodiment of aninput apparatus 8′ having an alternative keyboard 24′. As seen in FIG.16, keyboard 24′ includes: a first key 28 having a Roman “Q” character,a Thai sara ai maimalai character and a Thai maiyamok character thereon;a second key 28 having a Roman “W” character, a Thai sara am character,a Thai tho nangmontho character, and a Thai pho samphao characterthereon; a third key 28 having a Roman “E” character, a Thai pho phancharacter, a Thai tho thung character and a Thai do chada characterthereon; a fourth key 28 having a Roman “R” character, a Thai sara acharacter, a Thai sara u character and a Thai tho thong characterthereon; a fifth key 28 having a Roman “T” character, a Thai maihan-akat character, a Thai sara ue character and a Thai sara uucharacter thereon; a sixth key 28 having a Roman “Y” character, a Thaikho khwai character, and a Thai sara ii character thereon; a seventh key28 having a Roman “U” character, a Thai ro rua character, a Thai to taocharacter and a Thai no nen character thereon; an eighth key 28 having aRoman “I” character, a Thai no nu character, a Thai cho chan characterand a Thai paiyannoi character thereon; a ninth key 28 having a Roman“O” character, a Thai yo yak character, a Thai kho khai character and aThai yo ying character thereon; a tenth key 28 having a Roman “P”character, a Thai bo baimai character, a Thai cho chang character and aThai tho than character thereon; an eleventh key 28 having a Roman “A”character, a Thai fo fan character, a Thai ho hip character and a Thairu character thereon; a twelfth key 28 having a Roman “S” character, aThai ko kai character, a Thai do dek character and a Thai to patakcharacter thereon; a thirteenth key 28 having a Roman “D” character, aThai sara e character, and a Thai sara o character thereon; a fourteenthkey 28 having a Roman “F” character, a Thai mai tho character, and aThai maitaikhu character thereon; a fifteenth key 28 having a Roman “G”character, a Thai mai ek character, and a Thai mai chattawa characterthereon; a sixteenth key 28 having a Roman “H” character, a Thai sara aacharacter, and a Thai mai tri character thereon; a seventeenth key 28having a Roman “J” character, a Thai so sua character, and a Thai sorusi character thereon; an eighteenth key 28 having a Roman “K”character, a Thai wo waen character, and a Thai so sala characterthereon; a nineteenth key 28 having a Roman “L” character, a Thai ngongu character, and a Thai so so character thereon; a twentieth key 28having a Roman “Z” character, a Thai pho phung character, and a Thai khorakhang character thereon; a twenty-first key 28 having a Roman “X”character, a Thai sara ae character, and a Thai cho choe characterthereon; a twenty-second key 28 having a Roman “C” character, a Thai oang character, and a Thai cho ching character thereon; a twenty-thirdkey 28 having a Roman “V” character, a Thai sara i character, and a Thaiho nokhuk character thereon; a twenty-fourth key 28 having a Roman “B”character, a Thai sara uee character, and a Thai phintu characterthereon; a twenty-fifth key 28 having a Roman “N” character, a Thai thothahan character, a Thai mo ma character, and a Thai thanthakhatcharacter thereon; a twenty-sixth key 28 having a Roman “M” character, aThai sara ai maimuan character, a Thai lo chula character, and a Thaitho phuthao character thereon; a twenty-seventh key 28 having a Thai loling character, a Thai fo fa character and a Thai baht characterthereon; and a twenty-eighth key 28 having a Thai po pla characterthereon.

Thus, the disclosed and claimed concept provides keyboard layouts and amethodology that facilitates the entry of text in a language thatemploys non-Roman characters while at the same time still providing astandard QWERTY or similar keyboard adapted for the entry of text usingRoman characters in a conventional manner.

While specific embodiments of the disclosed and claimed concept havebeen described in detail, it will be appreciated by those skilled in theart that various modifications and alternatives to those details couldbe developed in light of the overall teachings of the disclosure. Forexample, while a physical keyboard 24 is described herein, it will beappreciated that the disclosed and claimed concept may be implemented inthe form of virtual keyboard provided on a touch screen. Accordingly,the particular arrangements disclosed are meant to be illustrative onlyand not limiting as to the scope of the disclosed and claimed conceptwhich is to be given the full breadth of the claims appended and any andall equivalents thereof.

What is claimed is:
 1. A handheld electronic device comprising; aprocessing apparatus comprising a processor; an input apparatuscomprising a plurality of input members and being structured to provideinput to the processor apparatus, a first set of the input members eachhaving a Roman character assigned thereto, at least some of the inputmembers in the first set of the input members having a first non-Romancharacter, a second non-Roman character, and a third non-Roman characterassigned thereto, wherein said non-Roman characters are from a firstlanguage having one or more rules that govern permissible charactersequences; an output apparatus structured to received output signalsfrom the processor apparatus; and a memory having stored therein anumber of routines which, when executed on the processor, cause thehandheld electronic device to be selectively switchable between: (i) aRoman character input mode, and (ii) a non-Roman character input mode,wherein in said Roman character input mode, each said Roman charactermay be selected and input into said processor apparatus for display onsaid output apparatus in response to actuation of the input member towhich it is assigned, and in said non-Roman character input mode, saidprocessing apparatus determines whether the handheld electronic deviceis in a shift mode after switching to the non-Roman character inputmode, and responsive to determining that the handheld electronic deviceis not in the shift mode, each first non-Roman character may be selectedand input into said processor apparatus for display on said outputapparatus in response to a first type of actuation of the input memberto which it is assigned, each second non-Roman character may be selectedand input into said processor apparatus for display on said outputapparatus in response to a second type of actuation of the input memberto which it is assigned, wherein upon the second type of actuation ofthe input member to which it is assigned, the first non-Roman charactercorresponding to the first type of actuation of the input member towhich it is assigned, is displayed and highlighted, prior to the secondnon-Roman character corresponding to the second type of actuation isdisplayed, and responsive to determining that handheld electronic deviceis in the shift mode, each third non-Roman character may be selected andinput into said processor apparatus for displaying on said outputapparatus in response to a third type of actuation of the input memberto which it is assigned, in response to an actuation of a first one ofthe input members, display on said output apparatus a first one of thenon-Roman characters that is assigned to the first one of the inputmembers, and based on said one or more rules that govern permissiblecharacter sequences in the first language, prevent display on saidoutput apparatus of a second one of the non-Roman characters in responseto an actuation of a second one of the input members having the secondone of the non-Roman characters assigned thereto immediately followingsaid actuation of said first one of the input members.
 2. The handheldelectronic device according to claim 1, wherein said routines, whenexecuted on the processor, further cause the processor to display athird one of the non-Roman characters provided on said second one of theinput members and different than said second one of the non-Romancharacters in response to said actuation of said second one of the inputmembers.
 3. The handheld electronic device according to claim 1, whereineach said first non-Roman character, said second non-Roman character,and said third non-Roman character is a Thai character.
 4. The handheldelectronic device according to claim 1, wherein said first type ofactuation comprises a single actuation of the input member and saidsecond type of actuation comprises a first actuation of the input memberfollowed by a second actuation of the input member within apredetermined time frame.
 5. The handheld electronic device according toclaim 4, wherein said third type of actuation comprises a singleactuation of the input member when said handheld electronic device is insaid shift mode.